Microsft has made hard statements about perfomance improvements in Longhorn. They claim that applications will load 15% faster than in XP, while boot time is decreased by 50%. They also claimed that Longhorn will be able to wake up from sleep in 2 seconds. Users should also expect half as many reboots during patching. Time to dust of those trustworthy stopwatches.

50% less system images does not refer to disk access. It refers to disk images made for corporate and OEM rollout. Longhorn will allow more flexibility in creating and maintaining system images. New imaages won't be required for various localizations, images can be directly updated and have patches integrated, etc.